Circuit breaker



Patented Dec. 19, 1950 CIRCUIT BREAKER George C. Woodward, Beaver, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 6, 1948, Serial No. 13,497

This invention relates to circuit breakers and more particularly to circuit breakers which are manually operable to open and close the circuit and which are automatically operated to open the circuit in response to predetermined abnormal conditions.

An object of the invention is to provide a small compact circuit breaker capable of being mounted in a small size wall outlet box.

Another object of the invention is to provide itself, both as to construction and operation, to-

gether with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read in conjunction with the accompanying drawing.

In said drawing:

Figure l is an elevational view of the circuit breaker with the cover removed and the parts shown in the closed-circuit position;

Fig. 2 is a sectional view taken on line IIII of Fig. 1 and looking in the direction of the arrows;

and

Fig. 3 is a sectional view similar to Fig. l but showing the circuit breaker in th manually open position or the reset position.

Referring to the drawing, the circuit breaker comprises a casing I I of molded insulating material and a cooperating cover I3 also of molded insulating material which is removabl secured to the casing I I at the open side thereof. A stationary contact I5 is mounted on a terminal I! of conducting material. The terminal I I extends through an opening I9 in one end wall of the casing and is loosely supported by means of a projection 2| of the casing and a terminal screw 23 which extends into a recess 25 in the projec tion 2 I. A spring 21 compressed between the terminal I1 and a spring seat in the base of the casing II provides contact pressure in the closed position of the breaker. minal I I when the contacts separate is limited by striking the upper wall of the opening IS. A

movable contact 29 is mounted on a switch arm.

3| supported on a pivot pin 33 which is pivotally mounted in corresponding holes in the side wall Movement of the ter- 10 Claims. (Cl. 200-416) of the casing II and in the cover I3. The switch arm 3| is biased to the open position by means of a spring 35 compressed between a spring seat in the casing II and the switch arm. A stop3l integral with the molded casing H is provided to limit the movement of the switch arm 3I in opening direction.

The switch arm 3! is normally restrained in the closed position by means of a latch 39 mounted on the lower end of a bimetal element 4 I. At its upper end the bimetal II is provided with a mounting foot 43 by which it is secured to a guide member 45. The guide member 45 is U-shaped and the legs thereof are slidably mounted for vertical movement in a guide slot 4! in the side wall of the casing II and a corresponding slot in the cover I3. At its upper end, the guide member 45 has a portion 49 that is formed over at right angles to the vertical portion and the bimetal element 4| is secured to the under side of the formed over portion. The ends of the formed over portion 49 are again formed at right angles to provide upwardly extending brackets 5I between which is mounted a pin 53. The pin 53 extends through a cam slot 55 formed in the inner portion 51 of an operating handle 59 of insulatin material. The operating handle 59 is provided with trunnions M which extend into recesses molded in the casing II and cover I2 to pivotally support the operating handle. The handle 59 projects outwardly through an opening 63 in the casing II to permit manual operation thereof.

The switch arm 3I is electrically connected by means of a flexible conductor 65 to the lower end of the bimetal element M and the upper end of the bimetal element 4| is similarl connected at the mounting foot d3 by means of a flexible conductor 61 to the inner end of an angular terminal strip 69. The terminal strip 69 extends through an angular opening in the end wall of the casing II and is provided with a screw 1! for connecting it in an electrical circuit. The circuit extends from the terminal II through the stationary and movable contacts I529, the switch arm SI, flexible shunt conductor 65, himetal element 4!, flexible shunt conductor 57 to the terminal 69.

When an overload occurs in the circuit controlled by the breaker, the bimetal element be comes heated and after it is heated a predetermined amount the lower end of the bimetal element deflects toward the right (Fig. 2) and effects unlatching of the switch arm 3!. As soon as the bimetal 4| has deflected far enough to release the switch arm 3I, the spring 35 acts to move the switch arm to the open position. The spring 21 causes the terminal I! upon which the stationary contact is mounted, to follow the movable contact until it strikes the wall of the opening l 9. The relative movement of the switch arm 3| and the terminal ll causes a desirable wiping action between the contacts l529, which tends to keep the contacts clean.

Before the contacts can be closed it is necessary to first reset and relatch the mechanism. This is accomplished by moving the operating handle 59 in a counterclockwise direction from the on position (Fig. l) to the ofi position (Fig. 3). During this movement the cam slot 55, acting on the pin 53 raises the guide member 45 and the bimetal element 4! so that the latch 39 wipes by the switch arm and assumes the position shown in Fig. 3 wherein the latch 39 is reengaged with the switch arm 3!. Thereafter the contacts are closed by rotating the operating handle 59 clockwise. from the off position to the on position.

During this movement the cam slot 55 moves the guide member at and the bimetal ii downwardly, the latch 33 engaging and moving the switch arm iii clockwise to the closed position. The cam slot 55 is provided with a slightly offset portion 55' winch, in the on position of the handle, engages the pin 53 and restrains the. parts in their closed position.

The. breaker may be manually opened by movement of the handle 59 counterclockwise from the on position to the off position. This move-- ment causes the cam slot to raise the guide member 45 and bimetai element ll to the ofi position permitting the spring 35 to move the switch to the open position as shown in Fig. 3. The contacts are manually closed in the reviously described manner.

The circuit breaker is trip-free of the operating mechanism, that is, even though the operating handle 5% and guide member 455 are held in the on position, the bimetal element will deflect when heated in response to an overload and release the s=.vitch arm 3 l.

The circuit breaker comprises a minimum number of parts and these parts are mounted in the casing without the use of any frame other than the casing itself, the parts being inserted through the open side of the casing and merely laid into recesses molded therein, and are held in proper position by the walls of said recesses and corresponding recesses molded in the cover. These features provide a circuit breaker which is simple and rugged in construction, reliable in operation and inexpensive to manufacture.

While the invention has been disclosed in accordance with the provisions of the Patent Statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made without departing from some of the essential features of the invention.

I claim as my invention:

1. A circuit breaker comprising a switch member biased to open position and movable to open and close the circuit, a bimetal element having latch means thereon normally engaging and releasably restraining said. switch member in closed position, said bimeta-l element being longitudinally movable to effect movement of said switch member to open and closed positions, a pivoted operating handle at all times connected tosaid bimetal element and manually rotatable to efiect reciprocal longitudinal movement of said bimetal element, and said bimetal being operable in re sponse to overload currents to release said switch member to thereby effect automatic opening movement of said switch member.

2. A circuit breaker comprising a pivoted switch member biased to open position and movable to open and close the circuit, a bimetal element releasably engaging and normally restraining said switch member in closed position and longitudinally movable to effect movement of said switch member to open and closed positions, a pivoted operating handle manually operable to effect reciprocal longitudinal movement of said bimetal element, connecting means at all times connecting said bimetal element to said operating handle, and said bimetal being operable in response to overload currents to disengage said bimetal element from said switch member to thereby effect automatic opening movement of said switch member free of said bimetal element and irrespective of the position of said, handle.

3. A circuit breaker including a pivoted switch arm biased to open position and. movable to open and close the circuit, a bimetal element releasably engaging said switch arm for normally restraining said switch arm in closed position, saidhimetal element being longitudinally movable to effect pivotal movement of said switch arm to open. and closed positions, a guide member separate from said switch arm for supporting and guiding said bimetal element, an operating handle at. all times connected to said guide member and operable to move said guide member and said bimetal. element to thereby effect movement of said switch arm to manually open and. close said circuit, and said bimetal element being operable in response to overload currents to release said switch arm. to

thereby effect automatic opening movement or said switch arm.

4. A. circuit breaker including a pivoted switch arm biased to open position and movable to open. and close the circuit, a bimetal element reieasably engaging and normally restraining said switch arm in closed position and longitudinally movable. to effect movement of said switch arm to open and closed positions, a guide member supporting and guiding said bimetal element for longitudinal movement, a pivoted operating handle tor moving said guide member and said bimetal element to thereby effect movement of said switch, arm. to. manually open and. close said circuit, a pin and slot connection connecting saidv guide member to said handle, and said bimeta-l element being operable in response to overload currents to. disengage said bimetal element fromsaid switch arm to thereby effect automatic opening movement of said switch arm free of said bimetalelement and irrespective of the position of said guide member.

5. A circuit breaker including a pivoted switch arm, means biasing said switchv arm to open position, a pivotal operating handle for moving said switch arm to a closed position and operable to permit said biasing means to move said switch arm to open position, a bimetal element releasably engaging said switcharm, ca a means on said handle normally holding said. bimetal element against longitudinal movement to holdsaid switch arm closed andv operable. upon rotative movement of said. handle to move said bimetal element longitudinally to effect rotative opening and closing movement of. said switch arm, guide means for supporting and guiding. said bimetal element in its longitudinal movement, and, said bimetal element being. operable in response. to overload, currents to. unl'atch. saidv switch. arm to thereby effect automatic opening movement of said switch arm.

6. A circuit breaker including a switch arm biased to open position and movable to open and close the circuit, a thermal element disposed to normally releasably restrain said switch arm in the closed position, means supporting said thermal element for longitudinal movement, a manual operating handle, a cam on said handle engaging a part movable with said supporting means to effect movement of said supporting means and said thermal element to open and closed positions upon movement of said handle to open and closed positions to thereby effect opening and closing movement of said switch arm, and said thermal element being operable in response to overload currents to release said switch arm to thereby effect automatic opening movement of said switch arm.

'7. A circuit breaker including a pivoted switch member biased to open position and movable to open and close said circuit, a bimetal element disposed to normally restrain said switch member in closed position, slidable means supporting said bimetal element for longitudinal movement, a

pivoted operating handle, cam means on said handle engaging said slidable means and operable upon movement of said handle to open and closed positions to move said slidable means to effect manual opening and closing movement of said switch members, and said bimetal element being operable in response to overload currents to release said switch member to thereby effect automatic opening movement of said switch member irrespective of the position of said handle.

8. A circuit breaker including stationary and movable contact means, biasing means biasing said stationary contact to provide contact pressure in the closed contact position, biasing means biasing said movable contact means in opening direction, operating means including a bimetal element, latch means on said bimetal element normally engaging and releasably restraining said movable contact means in closed position,

slidable means supporting said bimetal element e;

for reciprocal longitudinal movement, a manually operable handle having a pin and slot connection with said slidable means for actuating said slidable support means and said bimetal element to effect opening and closing of said contact means, and said bimetal element deflecting when heated a predetermined amount in response to overload currents to disengage said latch means from said movable contact means to thereby effect automatic opening of said contact means.

'9. A circuit breaker comprising a pivoted switch member biased to open position and movable to open and close the circuit, a pivoted operating handle rotatably movable between open and closed positions, a thermally responsive element forming a releasable mechanical connection between said handle and said switch member, cam means on said handle operable upon rotative movement of said handle between said openand closed positions to cause longitudinal movement of said thermally responsive element to thereby efiect rotative opening and closing movement of said switch member, and said thermally responsive element being responsive to overload currents to release said switch member to thereby efiect automatic opening movement of said switch member irrespective of the position of said handle.

10. A circuit breaker comprising a pivoted switch member biased to open position and movable to open and closed positions to open and close the circuit, a pivoted operating handle rotatably movable between open and closed positions, a thermally responsive element forming a mechanical connection between said handle and said switch member, means on said handle comprising a cam having a portion restraining said switch member in closed position in the closed position of said handle, said cam upon rotative movement of said handle between said open and closed positions causing longitudinal movement of said thermally responsive element to effect rotative opening and closing movement of said switch member, and said thermally responsive element being responsive to overload currents to release said switch member to thereby effect automatic opening movement of said switch member irrespective of the position of said handle.

GEORGE C. WOODWARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,094,963 Sachs Oct. 5, 1937 2,210,261 Sachs Aug. 6, 1940 2,229,412 Jennings Jan. 21, 1941 2,307,823 Coy Jan. 12, 1943 2,400,984 Dyer May 28, 1946 

